Grade 2 (age 7-8)

Four-digit Numbers

A four-digit number is built from four places: thousands, hundreds, tens, and ones. It has one place more than a three-digit number, the new thousands place, so 3527 means three 1000s, five 100s, two 10s, and seven 1s. You meet numbers this big when counting all the students in a school or the coins in a piggy bank. Here you can slide to change the number and study its blocks, then skip-count by equal jumps along a number line to reach big numbers quickly.

World of Thousands!

🏙️ What if your school had 1000 students?

①10 in a row → 100 in a class

②100 in 10 classes → 1000!

③Past 1000 → 4-digit number

Place Value of 4-digit Numbers

Change Number3527

💡 A New Place!

①Thousands place is new

②Tells how many 1000s

③Leftmost digit has the biggest value

Skip Counting

Start Number1000

Skip Amount100

🦘 Skip Counting Practice

①Add the same amount repeatedly

②Try by 10, 100, 1000

③Finding patterns makes counting fast

Summary

4-digit Composition

Thousands × 1000 + Hundreds × 100 + Tens × 10 + Ones × 1

4-digit numbers go from 1000 to 9999

Skip Counting

Start + skip + skip + ... = a regular sequence

Repeated addition of a fixed amount

🎯 Remember!

①4-digit numbers: 1000 to 9999

②Thousands digit determines the biggest value

③Compare from thousands first

④Skip counting helps with big numbers

⑤100 tens = 1000

Examples and Unit Test

Example 1

What 4-digit number has 3 thousands, 5 hundreds, 0 tens, and 6 ones?

Find each place value: 3×1000 = 3000, 5×100 = 500, 0×10 = 0, 6×1 = 6.

Add them all: 3000 + 500 + 0 + 6 = 3506.

▸ 3506

A 0 in the tens place means there is nothing in that place.

Example 2

Skip-counting by 100 from 2000, what are the next three numbers after 2000?

Skip-counting by 100 means adding 100 each time.

2000 + 100 = 2100, +100 = 2200, +100 = 2300.

▸ 2100, 2200, 2300

Skip-counting is a rule of repeatedly adding the same number.

Unit Test

What number is made of 4 thousands, 2 hundreds, 7 tens, and 5 ones?

①4275

②4725

③2475

④4257

▸ ① 4275

4 thousands = 4000, 2 hundreds = 200, 7 tens = 70, 5 ones = 5.

4000 + 200 + 70 + 5 = 4275.

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3-digit Numbers

Carry/Borrow Add-Sub